Transcript for Obama Visits Hartford, Conn., to Urge End to Gun Control Stalemate

assignment tonight and president obama is on the road making an emotional plea. You see him right there, just 40 from miles from the newtown shooting. Pressing lawmakers to punch through the stalemate and pass something on gun ntrol. Much of his agenda has been blocked and resistance is growing. So as the president scrambles for a compromise, he's taking dramatic steps. When he leaves connecticut tonight, 11 members from newtown will join him on air force one. A last hitch intense me human pitch. Abc chief white house correspondent jonathan karl starts us off. Reporter: The president portrayed his gun plan as a moral imperative. This is not about me. This is not about politics. This is about doing the right thing for all the families who are here that have been torn apart by gun ce. It's about them. And all the families going forward, so we can prevent this from happening again. Reporter: He inadvocacy the memory of those gunnedown in newtown four months ago. If there's one step we can take to keep somebody from murdering dozens of innocents in the span of minutes, shouldn't we be taking that step? Reporter: But two major parts of the president's plan, banning so-called assault weapons and high capacity ammunition clips are unlikely to pass. The measure that has the best chance, requiring background checks for all gun sales. To pass that, the president is hoping to have an unlikely ally. Republican pat tomby, who has a lifetime a rating from the nra and is one of the most conservative senatorings. He's trying to craft a compromise that would require background checks on all sales except between close relatives and friend. Gabby giffords and her husband are gearing up for a lobbying push this week, saying that improving background checks is something congress simply must do. Gabby will be incredibly disappointed, as I imagine a large part of this country will be if the universal background check bill is not passed here. Reporter: The newtown family members flying back to washington tonight with the president on air force one will be a big part of his push in congress. This week a senior official told me, there's no more effective advocate on this than a parent who's lost a child. I know they're hoping to push this compromise on background checks. Anything new on that? I can tell you I talked to some of the president's allies on the hill just a short while ago. I think it's a 50-50 chance they can get the compromise done and passed in the senate. The key factor is pat tomby, the republican senator, but also the how big a push do they make against this? Now to growing fears about a

This transcript has been automatically generated and may not be 100% accurate.

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